1. Field of the Invention
The invention relates to a stator of a motor applied to an alternating current motor (AC-motor), so as to advantage assembly, to reduce coil material, and to enhance the efficiency of motor.
2. Description of the Related Art
It has been over one hundred years since the prototype of motor has been developed. The motor converts electrical energy into mechanical energy. The mechanism of a motor is to induce electromagnetic force at magnetic poles of the rotor in a motor by the current flowing through the coil of an armature. By the repulsive force between a stator and the magnetic pole, a torque is induced to cause a rotation. This theory has been applied to develop various kinds of motors ever since. The types of stators are uncountable, such as those made of a natural magnet to magnetic poles made of silicon steel laminations. FIG. 1 shows a stator 10 of an ac motor (a shaded-pole motor). The stator 10 is made of silicon steel laminations 101. FIG. 2 and FIG. 3 are a top view of a conventional stator of a motor, while FIG. 3 is a cross sectional view taken along a cutting line I--I of FIG. 2. As shown in the figures, the stator 10 includes an exterior annulus 11 and an interior annulus 12 concentric thereto. Along a first imaginary central line of both the exterior and the interior annuli 11 and 12, there is a neck portion 121 connecting the exterior annulus 11 and the interior annulus 12 between exterior annulus 11 and the interior annulus 11. A second imaginary central line perpendicular to the first imaginary central line intersects the interior annulus 12 at two intersections. The interor annulus 12 has one opening 122 at each intersection. Thus, the interior annulus 12 is separated into two opposite magnetic poles 123 (N pole and S pole). A metal plate 124a and a metal plate 124b are filled each in the opening 122, respectively, to reduce the magnetic leakage. In addition, there is a trench 127 which further separates the magnetic pole 123 into two sectors. A metal ring 125 is disposed in the trench 127 (Typically called shaded coil). The metal ring 125 is often a single strip copper wire, or sometimes more than one lap. Insulating plates 126a, 126b are disposed over and under the stator 10. A coil 20 is wound along the neck portion 121 between the exterior annulus 11 and the interior annulus 12. The coil 20 is wrapped by an insulating plate 126a, 126b. While a current is flowing through the coil 20, a magnetic flux is induced at the magnetic pole 123. With the disposition of the metal ring 125 in the magnetic pole 123, after the magnetic flux is induced in the magnetic pole 123, the magnetic flux of the magnetic pole 123 (the smaller one) is affected by the induced current in the metal ring 125. Thus, the rotor (not shown) installed at center of the interior annulus 12 can be rotated.
Being restricted by the structure of the stator 10, to install the coil 20 into the stator 10 is complicated. The coil 20 has to be wound and formed in advance (Currently, an automatic winding machine has replaced the conventional manual winding process). The coil 20 is wound and formed by tape to prevent from being loosened. The coil 20 is then inserted through the openings 122 which have been encased by the insulating plate 126a, 126b and fixed on the neck portion 121. The openings 122 are sealed by the metal plates 124a,124b to complete the assembly of the stator 10.
However, the are stator of a motor has at least the following disadvantages:
(1) The assembly procedure is so complicated that the coil 20 has to be formed before being inserted into the magnetic pole 123 of the stator, and fixed on the neck portion 121. A part of the assembly procedure is carried out manually, so that the cost is high. PA1 (2) The coil 20 is encased in the conventional stator. The openings 122 of the magnetic pole 123 have to be wider than the width of the coil 20. The coil 20 is often formed with a widened diameter to ensure the safety of manufacturing. This structure thus causes the coil 20 encased on the neck portion 121 to be loosened. A lot of coil material is consumed, so that the fabrication cost is raised. The large consumption of the coil material also increases a lot of energy consumption to decrease the efficiency of the motor. PA1 (3) As mentioned in (2), a certain thickness is required for the coil 20. When the gap of the openings 122 is excessively large, a serious magnetic leakage of the stator is caused thereby. The magnetic field of the magnetic poles in the stator is reduced to cause a smaller output torque. Even with the metal plate 123 being filled into the openings 122 to reduce the magnetic leakage, the consequent effect is also limited (The increase on the cost of work process is additionally bound to raise the aggregate cost of the motor)